US2293549A - Method and apparatus for heating billets - Google Patents

Description

Aug. 18, 1942. s. F. KEEN ER 2,293,549

METHOD AND APPARATUS FOR HEATING BILLETS Filed May 20, 1939 2 Sheets-Sheet 1 glwum I SAM F- KEENER Aug, 18, 1942. s. F. KEENER METHOD AND APPARATUS FOR HEATING BILLETS an F. KEENER Patented Aug. 18, 1942 UNITED STATES PATENT OFFICE 2,293,549 METHOD AND APPARATUS FOR HEATING" BILLETS Sam F. Keener, Salem, Ohio Application May 20, 1939, Serial N0. 274,760

Claims.

This invention relates to an improved method and apparatus for heatingmetal billets and more I particularly to the uniform heating of such billets customarily employed in the production of seamless tubes preparatory to the piercing operation of the process producing the tubes. The invention, by reason of the utilization of the im- I proved billet. heating method and apparatus of braced a heating furnace of the inclined hearth type in which the billets are manually rolled down, a heating furnace of the walking beam type in which suitable mechanical contrivances are employed to propel the billets through the furnace, and a billet heating furnace of the batch type in which the billets are simply deposited on suitable fixed supporting surfaces and manually periodically moved to effect uniform heating of them. Considerable manual labor is required in the operation of furnaces of the first and last mentioned types, as the billets must be handled manually and in furnaces of the sloping hearth type a multiplicity of doors must be provided along the side walls thereof to afford access to the billets as they proceed along the hearth. In

' paratory to the piercing operation aforesaid emaddition, the charging opening at the upper end of the furnace and the discharging opening at the lower end of the furnace, together with the inclined nature of the furnace, create a stack effect therein and this, together with the openings in the side walls of the furnace, makes the maintenance of proper heat distributionwithin the furnace a very diflicult matter. In operation, furnaces of this character allow large volumes of hot gases to rise out of the upper portions of the furnaces and admit correspondingly large volumes of cold air in the lower portions, which tends to result in a cool discharge hearth requiring closing of the furnaces and interruption of the production process. Also, the introduction of large volumes of fresh air renders the mamtenanceof 'the advantageous reducing atmosphere within the furnace impossible, causing scaling of the billets. By reason of the substan- Characteristic of the operation of the walking beam type of furnace is the streaking of the billets due to the portions thereof which are immediately adjacent the supporting and propelling I beams being cooled, the beams being water cooled in accordance with usual practice; The nonuniformity of heating resulting from the streaking renders the billets unsuitable for working and, therefore, in such furnaces a second stationary hearth is provided at the discharge end of the beams on which the billets may be supported for a,short interval of time to insure elimination of the streaks before they are transferred to the piercing mill or other working apparatus. The uniform heating of the streaked billets on suchv secondary hearth requires some manual manipulation and sound judgment on the part of the operator tending such billets. The apparatus utilized in a furnace of the walking beam type requires considerable maintenance and, since it is diflicult to seal the special hearth employed because of the mechanical supporting and moving members therefor, it is difficult to control the pressure and atmosphere within the furnace. Also, since the secondary hearth is sloped to facilitate manipulation of the streaked billets, a

stack effect, similar to but less in extent than skilled manual labor and limitations of plant layout since the billets must all be continuously moved to insure their uniform heating and therefore sumcient usable space provided to accommodate the operators. Inasmuch as a plurality of discharge points must be provided for a furtial hot gas losses considerable fuel, in excess nace or furnaces of the batch type to supply provision of an improved method and apparatus for heating the billets preparatory to the piercing operation and the provision of an improved arrangement of such apparatus relative to the other essential equipment of the plant whereby a higherrate of production may be maintained. a more uniform product produced, and less labor required for such production. These objects are accomplished, according to my invention, by employing a circular furnace having a rotary hearth therein and having a discharge point adjacent 'tgthe'piercing mill and a charg g point adiacent to the discharge point. For reasons to be hereinafter specifically set out, the employment of a furnace of this type for the purpose and in the relative position indicated results in a more nite economies are effected in the operation of the billet handling and heating phases of the tube production process. 1

Another object of the invention is the provision of an improved arrangement'of apparatus for handling and heating billets preparatory to their working in a piercing mill whereby the billetswill be uniformly heated and will reach the piercing mill at a uniform temperature. with a minimum of apparatus required for the handling and heating. "Yet another object of the invention is the provision of apparatus for the purposes stated which is operable with a minimum of labor, which reduces the formation of scale on the billets, and which is rugged in service.

These and other gb ie0 ts and advantiag oi tne invention wl11 become"apparent from a consideration of the accompanying drawings and the foll2 and I3." Adjacent openings l6 and H are provided in the outer furnace wall l3 to allow passage of the billets into and out of the furnace, respectively. I

Extending outwardly from each of the openings l6 and I1 is a framework 22 adapted to mov-' ably support a material handling machine 2| commonly termed a charging machine. In accordance with usual practice, the machine 2| may consist of .a carriage for the support of the drive and control equipment and the operator.

and a water cooled peel 23 carried by and extending outwardly from the carriage. As is well understood, the peel 23 ismounted for considerable manipulative movement and as employed in the apparatus of this invention is provided at its outer end with a pair of tongs 24 which may be clamped about the billets being handled to deposit the same within or withdraw the same from the furnace as the case may be.

Associated with the charging machine 2| adjacent the inlet door l6 of the furnace is a transfer table I 9 onto which cold billets may be placed and moved beneath the tongs of the machine preparatory to their being charged into the furnace. A transfer table 20 is associated with the charging machine adjacent the discharge opening ll of the furnace to receive the heated billets as they are withdrawn from the furnace by the machine. Table 20 abuts against a conveyor 26 which is operative to quickly move the heated billets to the vicinity of the piercing mill or mills lowing detailed specification wherein there is specifically disclosed a billet heating furnace constructed in accordance with my invention and a lay-out for a portion of a plant for the production of seamless tubes.

In the drawings:

Figure 1 ma plan view of a portion of a plant for the production of seamless tubes arranged according to my invention, a portion of the billet heating furnace being shown in section to illustrate the manner in which the billets are charged into the furnace and carried therein;

Fi ure 2 is a vertical section through the apparatus of Figure 1, said section being taken along the line II-II of Figure l; and

Figure 3 is a fragmentary section along the line III-III of Figure 1.

Referring now to Figure 1 of the drawings, which diagrammatically illustrates that portion of a seamless tube production plant with which theipresent'invehtion is corfiie'rned, reference numeral Ill indicates generally a continuous billet heating furnace and reference numeral ll indicates a piercing mill for. performing the first working operationon the billets in the tube production process. Furnace i0 is circular in planhaving a cylindricalinnerside wall l2, [similar I center is coincident with the centers of the walls ll of the plant. For efiicient handling of the material the axis of the mill H is preferably parallel with the general longitudinal axis of theconveyor 26, a transfer table 21 being employed to move the heated billets from conveyor 26 to mill ll. Piercing mill II is preferably placed on the same side of the conveyor 25 as the furnace charging machines and in the event that two such mills are to be employed in combination with the furnace, they may be positioned on either side of the conveyor as illustrated in Figure 1an additional transfer table 28 being emplgyed to move the heated billets to the second in 1.

Referring now more particularly to Figure 2 of the drawings, the billet heating furnace I0 is built up between two concentric series of buckstays 3lthe functions of which are to provide lateral and vertical support for the side walls l2 andv l3 and support for the gas, air and flue ducts to be later described. A circular channel 32 is secured to the inner surface of the outer ring of members 3| adjacent the lower ends thereof and this, together with a multiplicity of circularly arranged members 33, supports the side walls of the furnace. Furnace hearth l5 which may be of solid refractory brick construction as shown or which may be provided with piers for supporting the material in order to provide circulation of gases all around the billets is supported on a suitable structural steel platform 41, the latter being carried by a number of wheels 48l9 (the inner or outer set being flanged as at 48) traveling on the rails circles 50-5l. Rails ill- M are supported on a frame worki ithe'latter as well as the entire furnace being supported on a suitable concrete base 30.

Y Evenly spaced about the peripheries of the walls l2 and 13 of the furnace and intermediate the burners 38 are the passages 35 which open to the space within the furnace in a horizontal plane substantially as low as or lower than the billet supporting surface of the hearth I5 and which extend upwardly through the tops of the walk to communicate with the tubular manifolds 36 and 31 positioned immediately above the walls I! and I3, respectively. As indicated in Figure 2| and other apparatus requiring human operatives. A-better control may therefore be exercised over the functioning of the plant and the'nur'nber of employees required for manning the plant may be reduced. In-operation, with the furnace previously heated, cold billets deposited on table l, the manifolds 36 and 31 are connected through conduits 84, 68 and a motor driven exhauster unit 35 with a stack 63. Pressure within the furnace may be controlled by operation of' the unit 35 but if the steel; 36 is of sufllcient height, the unit 65 may be dispensed with and the pressure controlled by means of dampers. Also, it should be apparent that recirculating systems and other 'known arrangements for'controlling the pressure withinthe furnace may be satisfactorily employed in connection with the billet heating furnace of this invention since the furnac is entirely closed except for. the small openings i6 and I1 existent when the furnace is being charged and discharged. When the latter operations are not in progress, openings l6 and I! are closed by the sliding doors 45. Note Figure 2.

Hearth I5 is sealed from below by sand seals which consist of quantities of sand in the circular troughs 54 and 56 carried by members 33 and the cylindrically formed plates 55 and 51, the

lower ends of which extend down into the sand carried by troughs 54 and 58, respectively. Plates 55 and 51 are secured to the sides of the hearth I 5 and inasmuch as they are circularly concentric with the troughs the seals are effectively maintained even during travel of the hearth. A shoulder is provided at each of the inner and outer edges of the hearth and grooves I 60 and BI are provided on the shoulders to retain scale and other foreign matter dropping from the hearth proper, thereby preventing such material from becoming lodged in the seals or between the sides of the hearth or hearth support and the furnace walls l2 and I3, whereby the proper functioning of the seals and the rotation of the hearth will not be interfered with.

If it is thought. necessary or desirable to turn the billets on the hearth as the hearth is rotated there may be provided. in accordance with the present invention, a pivoted bar or other member 10 suspended from the furnace roof ll (Figure 3) and having a curved lower'surface H to engaze and override the billets 63 as the latter I move underneath on the hearth. Member 10 has sufficient mass or, if required, a biasing means is employed, to insure sufllcient frictional contact between the surface H and the billets 6 3to rotate' the latter approximately 180 during such contact.

The furnace and its ancillary equipment are arranged relatively to each other and to the piercing mm as indicated in Figure 1 which results in the grouping of the charging machines.

I9 are picked up by the adjacent charging ma-- ,chine 2| and moved radially inward through the opening it and deposited in a radial position on the hearth IS. The charging continues as the hearth revolves and when the billets reach the opening l'l after having traversed substantially the entire length of the furnace, they will be engaged by the tongs 24 of the machine 2| used for unloading, withdrawing from the furnace, and deposited on thetable 20 from whence they will pass to the piercing mill. During normal operation of the plant, the charging, heating, and

discharging of the billets continues uninterruptedly and by reason of the space efficiency of the rotary furnace, the billet heating capacity of the plant will be adequatefor all plant requirement.

It should be observed that by reason of the manner in which the billets are charged into and withdrawn from the furnace; i.. e., longitudinally, 'the size of the openings requiredin the degree of scaling caused by contact of fresh air transfer table 20.

with the heated billets is also minimized. In addition, this method of handling the billets utilizes'more efficiently the space on the hearth within the furnace and enables a relatively simple arrangement, as shown in Figure 3, to be employed to automatically turn the billets, if required, during their travel through the furnace.

For reasons pointed out above and for the additional reasons that the billets are constantly moved under the flames and that a much better distribution of heat is obtained within the furnace, a more satisfactory heating. of the billets can be effected. In this furnace the gases are caused to swirl entirely around the furnace and to move downwardly to the hearth and outwardly therealong to the inlets to the ducts 35 all of which results in a more uniform distri- I I bution of heat within the furnace and more rapid heating of the billets. Such heating is accomplished without streaking the billets and without any manual manipulation of the same.

The present invention provides. a method and apparatus for heating billets inwhich the heating is thoroughly and economically accomplished substantially automatically-the only labor required being the two operators required foroperating the machines 2! and an engineer in charge of the operation of the furnace. The uni-. formly heated billets all leave the furnace through the opening I! and the length of travel of all the billets from the furnace to the piercing It should now be apparent that I have provided an improved method of heating and handling metal billets preparatory to their utilization in tube manufacturing and other processes and that such method is capable of being carried out l.- In apparatus for making seamless tubes, the

combination with a piercing mill of means to uniformly heat the cylindrical billets preparatory to their utilization in the mill, comprising a heating furnace having inner and outer concentric cylindrical walls, a continuous rotary hearth positioned between said walls and adapted to rotate within the furnace, openings in said outer wall for the passage of billets into and out of said fumaceacharging machine adjacent said furnace opposite each of said openings, said machines being operative to move said billets longitudinally into and out of said furnace; a conveyor for moving the'h'eated billets from the furnace to the vicinity of the piercing mill, the billet entering end of said conveyor being adjacent the machine opposite the billet discharging opening of said furnace.

2. In apparatus for' making seamless tubes. the combination with a piercing mill of means to uniformly heat the cylindrical billets-preparatory to their utilization in the mill, comprising a heating furnace having inner and outer concentric cylindrical walls, a continuous rotary hearth positioned between said walls and adapted to rotate within the furnace, openings in said outer wall for the passage of billets into and out of said furnace, a conveyor for longitudinally moving the heated billets from the furnace outlet to the vicinity of said mill, said conveyor extending outwardly from the furnace.

3. In apparatus for making seamless tubes, the combination with a piercing mill of means to uniformly heat the cylindrical billets preparatory to their utilization in the mill comprising a heating furnace having inner and outer concentric cylindrical walls, a continuous rotary hearth positioned between said walls and adapted to rotate within the furnace, adjacent openings in said outer wall for the passage of billets into and out of said furnace, adjacent charging machines opposite said openings and adapted to move cold billets through one of said openings onto said hearth and to move heated billets from said hearth through the other of said openings, a battle wall within said furnace between saidlopenlugs, and means to move the billets from one of said machines to said mill.

4. In apparatus for making seamless tubes, the

uniformly heat the cylindrical billets preparatory to their utilization in the mill comprising a heating furnace having inner and outer concentric cylindrical walls, a continuous rotary hearth out of said furnace, means to charge cold billets I through one of said openings and onto said hearth, means to withdraw heated billets from said hearth through the other of said openings and means to transfer heated billets from said last mentioned opening to said piercing mill.

5. In apparatus for making seamless tubes, the combination with a piercing mill of means to uniformly heat the cylindrical billets preparatory to their utilization in the mill comprising a heating furnace having inner and outer concentric,

cylindrical walls, a continuous rotary hearth positioned between said walls and adapted to rotate within the furnace, circumferentially spaced openings in the outer furnace wall for the passage of billets into and out of said furnace,

a 'baflie wall within said furnace between said openings, the opening for the passage of billets out of said furnace being located on the side of said furnace adjacent said mill.

'1. In apparatus for making seamless tubes, the

combination with a piercing mill of means to uniformly heat the cylindrical billets preparatory to their utilization in the mill comprising a heating furnace havinginner and outer concentric cylindrical walls, a continuous rotary hearth positioned between said walls and adapted to rotate within the furnace, openings in the outer wall of said furnace for the longitudinal passage of billets into and out of said furnace, means to move said billets longitudinally into and out of said furnace and to arrange said billets radially .on said hearth, and means to move said billets to said mill.

8. In apparatus for making seamless tubes, the combination with a piercing mill of means to uniformly heat the cylindrical billets preparatory to their utilization in the mill comprising a furnace having concentricallyarranged inner and. outer walls and a continuous hearth between said walls, means mounting said hearth for rotative' ,one of said openings and to deposit the same combination with a piercing mill of means to positionedbetween said walls and adapted to rotate within the furnace, openings in said outer wall on the side of said furnace adjacent said piercing mill for the passage of billets into and radially on said hearth, means positioned in the path of travel of said billets through the furtransfer and uniformly heat the solid cylindrical, billets preparatory to their utilization in the mill,

comprising a heating furnace having inner and outer concentric cylindrical walls, a continuousrotary hearth positioned between said walls and adapted to rotate within the furnace, openings in said outer wall for the passage of billets into and out of said furnace, a charging machine adjacent said furnace opposite each of said openings and generally aligned with radial lines extending from the center of said furnace through said openings, a transfer table extending at right 5 anglesfrom the charging machine adjacent the charging openings of said furnace, said machines being adjacent to each other and being operative to move said billets longitudinally into and out of said furnace, and a conveyor for moving the heated billets generally endwise from the furnace to the piercing mill. 1

10. The method of producing seamless tubes form desired temperature upon withdrawal from the furnace, moving said billets directly from said furnace to a piercing mill, and piercing said billets.

SAM F. KEENER.

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